常用知识点集合（慢慢更新）

1.//状态栏及背景  当一个页面需要navigation的样子 却又不要navigation时 可以这样加一个view，注意是从0开始

UIView * statusBarBgView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, 64)];

statusBarBgView.backgroundColor = REDCOLOR;

[self.navigationController.view addSubview:statusBarBgView];

2.xib拖的UiScrollView,不能禁止上下，或者左右滑动，在如下地方设置

禁止上下滚动选箭头那个，禁止水平滚动选下面那个

在代码中在配合bgScrollView.contentSize = CGSizeMake(你要的宽度, 0);

就可以禁止上下滚动了

3.使用UIAlertController

UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"请选择" message:@"" preferredStyle: UIAlertControllerStyleActionSheet];

UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:nil];

UIAlertAction *photographAction = [UIAlertAction actionWithTitle:@"拍照" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {

[self takePhoto];

}];

UIAlertAction *albumAction = [UIAlertAction actionWithTitle:@"去相册选择" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {

[self pushImagePickerController];

}];

[alertController addAction:cancelAction];

[alertController addAction:photographAction];

[alertController addAction:albumAction];

[self presentViewController:alertController animated:YES completion:nil];